When designing a unit including a plurality of function blocks, such as an engine of a vehicle, it is necessary to consider not only matters concerning the engine performance but also mountability and assembly of the engine onto the vehicle, factors such as performance and strength of the function blocks, and aspects related to productivity, such as the production facilities and the man-hours required for production. It is therefore important that in an automobile manufacturer designs be planned not just by an engine design team alone, but in cooperation with a production engineering team in charge of production and processing techniques for each of the function blocks. Conventionally, after determining a target for an engine design, the design team first designs the basic shape of the overall engine. Considerations related to the production engineering team are most commonly not taken into account until after the basic shape has been substantially decided and the prospective design of the overall engine design is already in view. FIG. 9 is a flowchart showing a common procedure for designing an engine, shown as a conventional example procedure for designing a unit including a plurality of function blocks.
In the basic specification setting step S1, the basic specifications are determined after the engine design target is given. For example, the design target may be defined as an engine type such as a V-6 gasoline fueled engine, a displacement such as 3.5 liters, a predetermined value of target output, and the like. The basic dimensions of the individual engine components is determined based on such design criteria.
In the basic cross-section designing step S3, the basic cross-section of the engine is designed in accordance with the basic specifications, and a drawing is created. In the basic skeleton designing step S5, a skeleton view including positions for the respective function blocks is designed and illustrated in accordance with the basic cross-sectional view. Further design is subsequently accomplished by incorporating details of each of the function blocks into this skeleton view. The steps of S3 and S5 may be executed in manners other than those described above.
The basic shape designing step S7 is for incorporating the details of the function blocks into the skeleton view. In this step, various design aspects are performed while taking into account factors such as the outer shape and positional arrangement of each function block and the relationships between the function blocks, such that the overall engine achieves the design targets. During the steps up to S7, requests concerning production technique requirements imposed by the design are conveyed from the design team to the production engineering team. However, as it is still difficult at this stage to fully present the whole aspect of the engine to those other than the members of the design team, no systematic discussions are held between the design team and the production engineering team. Accordingly, the steps up to S7 to design a new discrete engine for each design target, determine the basic shape, and bring the prospective design of the overall engine in view are executed almost entirely by the design team.
After the basic shape design has been completed so that design team can present the engine to others, the production technique consulting step S9 is performed to intensively consult on matters concerning production technique requirements in accordance with the basic shape design.
In the raw material shape designing step S11, the shapes of raw materials prior to machining are designed for the entire engine. In this stage, upon reviewing the production technique requirements requested by the basic shape design, aspects of the basic shape design that should be altered to accommodate the circumstances of production techniques are modified in the raw material shape design, where possible. Based on this raw material shape design, metal, wooden, or other molds for the engine frame and the function blocks are designed.
In the product shape designing step S13, the product shapes after machining are designed for the entire engine based on the raw material shape design. As in S11, accommodations for matters concerning the production techniques are made in the product shape design, where possible. Machining steps, processes, tools and jigs, facilities, and the like are then determined based on the product shape design.
In the fabricating step S15, the engine is fabricated using the molds formed in accordance with the raw material shape design and by performing the machining processes in accordance with the product shape design.
In the evaluating step S17, tests are performed to determine whether the fabricated engine achieves the design targets. Further, the engine is evaluated for its mountability and assembly onto a vehicle, the strength of each of the parts, and the like. When problems are found as a result of the evaluation, the problems are dealt with by returning to the proper step in the engine designing procedure.
As described above, in conventional procedure, the design team designs a new discrete engine for each design target, determines the basic shape, and brings the prospective design of the overall engine in view before consulting with the production engineering team.
In a conventional procedure as described above, although the engine design team and the production engineering team cooperate and consult each other on matters related to both engine performance and production techniques, consultations with the production engineering team conventionally take place only after the design team has already designed a new discrete engine for each design target, determined the basic shape, and brought the prospective design of the overall engine in view. For this reason, it is often difficult to include or reflect in a new design the matters concerning production techniques performed for past design examples. Furthermore, as accommodations to matters concerning the production techniques are made in later stages of the designing procedure, the accommodations can often only be included with great difficulty. Similarly, as mountability, assembly, strength, and the like are not evaluated until a later stage, it is also often difficult to incorporate design modifications determined as necessary after that evaluation. As such, the conventional design process is problematic in that significant portions of the designs must be redone, increasing the workload and prolonging the time required for development.